When The Beatles crooned “I’m So Tired,” they aptly described a sleepless night fuelled by upset over a relationship gone wrong. And that certainly describes one form of weariness.

But fatigue is something quite different, medically. It’s a recognized condition that’s distinct from apathy, exercise intolerance, weakness or lack of strength, or tiredness. It can be acute, lasting less than a month — and can be related to everything from overtraining to insomnia and temporary stress.

Or it can be chronic, persisting for months. In such cases, it may be a symptom associated with sleep apnea; anemia; medications; neurological conditions such as multiple sclerosis or Parkinson’s; cancer and cancer treatment; autoimmune diseases such as lupus or rheumatoid arthritis; mental health challenges such as depression; low thyroid function; or chronic stress and anxiety. In some cases, it’s a symptom of chronic fatigue syndrome (characterized by persistent fatigue for six months or more and other symptoms). Whatever the cause, a nap or sound night’s sleep doesn’t relieve it.

How you experience and react to fatigue is influenced by everything from your psychological outlook, personality type and life experience to your overall health. That’s why doctors have developed a new way to measure its impact, called fatiguability. It assesses how fatigued you feel in the context of your everyday activities. They have discovered that while one person may struggle with an activity, another person who reports similar fatigue may not get so worn down by it. They have a lower fatiguability score! That helps doctors tailor therapies and medical interventions to each individual.

How common is fatigue? Fatigue is estimated to account for 10 million doctor visits in the U.S. annually. A Centres for Disease Control and Prevention survey looking at fatigue for the years 2010-2011 found that among adults 18 to 44, women were nearly twice as likely as men (15.7 per cent versus 8.7 per cent) to often feel very tired or exhausted. A recent study published in BMJ Open found that fatigue had increased. In their sample, 20 per cent of folks ages 45 to 86 reported fatigue.

Important fact: The researchers stressed that in older folks, fatigue shouldn’t be viewed as expected or related to aging but should be seen as a possible signal of an underlying health condition that needs to be addressed.

What should you do about persistent fatigue?

When fatigue is persistent, upsetting and interferes with everyday living, you want to take effective action to alleviate it. Step numero uno is to upgrade your nutrition. You want to adopt an anti-inflammatory diet that excludes added sugars and syrups, highly processed foods, refined grains, and red and processed meats.

A recent study in the journal Nutrients found that “a balanced diet with whole grains high in fibres [100 per cent whole!], polyphenolrich vegetables [cruciferous veggies, legumes, dark leafy greens] and omega-3 fatty-acid-rich foods [salmon and sardines] might be able to improve disease-related fatigue symptoms.” We bet it will also help people with chronic stress or anxietyrelated fatigue.

Next, you want to walk or do other moderate exercise as much and as often as you comfortably can. (The exception may be if you have chronic fatigue syndrome. In which case, ask your doc before exercising.) If your fatigue is related to chronic stress, anxiety or depression, exercise will help manage those emotional challenges. And fatigue related to neurological conditions such as MS and various cancers is also greatly improved with exercise, including aerobics, resistance training, yoga and tai chi.

Equally important is working with your doctor to determine if you have an underlying medical condition (diagnosed already or not) that’s triggering fatigue.

— Ask for an evaluation to determine your fatiguability score.

— Also ask your doctor or pharmacist if fatigue could be the side effect of any medications or combination of medications you’re taking. Make adjustments if needed.

— Lastly, if you are diagnosed with chronic fatigue syndrome, look for a specialist in your area to work with.

-MICHAEL ROIZEN, M.D., AND MEHMET OZ, M.D.